Cells of the symbiotic prochlorophyte Prochloron didemni were separated from its ascidian partner, thylakoids isolated, treated to liberate chlorophyll-containing complexes, and negatively stained preparations observed by transmission EM. The image shows an averaged top view of a chlorophyll-photsystem II super complex. The overview shown in CIL 39146 illustrates the range of particle types in the preparation.